2.3 Container ships greater than 100 m

 These requirements apply to containerships greater than 100 m in length as defined in section 2 (Definitions) of the Introduction. They may also be applied to other cargo ships in this length range with considerable flare or large water plane areas. The Administration may apply the following criteria instead of those in part A, 2.2.

  2.3.2.1 The area under the righting lever curve (GZ curve) should not be less than 0.009/C metre-radians up to ϕ = 30° angle of heel, and not less than 0.016/C metre-radians up to = 40° or the angle of flooding ϕf (as defined in part A, 2.2) if this angle is less than 40°.

  2.3.2.2 Additionally, the area under the righting lever curve (GZ curve) between the angles of heel of 30° and 40° or between 30° and , if this angle is less than 40°, should not be less than 0.006/C metre-radians.

  2.3.2.3 The righting lever GZ should be at least 0.033/C m at an angle of heel equal or greater than 30°.

  2.3.2.4 The maximum righting lever GZ should be at least 0.042/C m.

  2.3.2.5 The total area under the righting lever curve (GZ curve) up to the angle of flooding ϕf should not be less than 0.029/C metre-radians.

  2.3.2.6 In the above criteria the form factor C should be calculated using the formula and figure 2.3-1:

where:

• d = mean draught (m)

• D' = moulded depth of the ship, corrected for defined parts of volumes within the hatch coamings according to the formula:

  

• D = moulded depth of the ship (m);

• B _D = moulded breadth of the ship (m);

• KG = height of the centre of mass above base, corrected for free surface effect, not be taken as less than d (m);

• C _B = block coefficient;

• C _W = water plane coefficient;

• l _H = length of each hatch coaming within L/4 forward and aft from amidships (m) (see figure 2.3-1);

• b = mean width of hatch coamings within L/4 forward and aft from amidships (m) (see figure 2.3-1);

• h = mean height of hatch coamings within L/4 forward and aft from amidships (m) (see figure 2.3-1);

• L = length of the ship (m);

• B = breadth of the ship on the waterline (m);

• B _m = breadth of the ship on the waterline at half mean draught (m).

 The shaded areas in figure 2.3-1 represent partial volumes within the hatch coamings considered contributing to resistance against capsizing at large heeling angles when the ship is on a wave crest.

  2.3.2.7 The use of electronic loading and stability instrument is encouraged in determining the ships trim and stability during different operational conditions.